Prxparation



Reissued Sept. 10,1929. 7 I

UNITED STATES PATENT OFFICE,

JOSEPH BLUMENFELD, OF LONDON, ENGLAND ASSIGNOR, BY ASSIGNMENTS, TO COMMERCIAL PIGMENTS CORPORATION, A COBCBOBATION OI DELAWARE.

. I PREPARATION or TITANIUM n'znaoxinn.

Ho Drawing; Original No. 1,504,672, dated August 12, 1924, Serial No. 690,658, filed February 4, 1821. Application for reissue filed August 1928. Serial No. 128,322.

DIVISION A.

The invention relates to the hydrolytic treatment of solutions of titanium oxide in sulphuric acid with the object of preparin the hydroxide of titanium. 5 %uch.solutions are obtainedby treating titaniferous products or minerals, such as ilmenite, with sulphuric acid.

The chemical composition of these solutions may vary within fairly wide limits.

, The two most important variables are the concentrations of TiO and H SO Solutions containing from 100 to 400 grins. TiO, per litre-are of the usual'strengths which have to be treated. For a molecule of TiO tlie solution should contain -12 or even more molecules of 11 80 .It has now been found that the yield of titanium hydroxide obtained by hydrolytic precipitation of such solution (heated at 2 about 100 C. during a certain time) as Well as its properties, such as the rate of decantation, filtrability, state of subdivision of grain, colour after calcination, etc, depend not only on the final state of the systom subjected to" hydr-ol'ytic treatment but they dependalso upon certain transformations Jvvhichthe constituents of the solution undergo before and during the precipitation of the titanium hydroxide and also upon the way in which this final state of reaction is brought about.- In efiect, the solution of TiO in H 80 brought to a desired concentration either by' dilution or. by concentra tion, is heated to the boiling point in order to produce the hydrolysis and becomes opaque after a comparatively long time, but

7 if the content in H SO combined with TiO -neglecting other bases, is equal to or exceeds 100 ms. per litre, a very poor yield in 40 titanium hydroxide is obtained. Moreover,

the precipitate thus obtained, even if filtra- 'ble, is only filtered with great difliculty.

The object of the present invention, therefore, is to obtain a satisfactory precipitate 5 (from the point of view of yield, filtrability and other properties) in a short time from solutions of the type mentioned above even in high concentrations.

The invention consists in preparing tita- 59 nium oxide or hyroxide by hydrolytic precipitation. by difiusion of titanium from one solution into another underthe action of differential concentration andpreferably also temperature. i

The invention further consists in prepar mg titanium oxide or hydroxide by by drolytic precipitation by diifusion of titanium from one solution 1nto anotherac'celer- V y mixed precipi- Generally, the methods employed are asfollows i (1)v The solution obtained by reacting on' the titanium material with sulphuric acid,

heated to a temperature exceeding 60 0., is covered. with a layer of coldwater orhot water, either pure or containing such substances as may favour the process such, for example, as H SO H PO Al,(SO,') 5, SQ

presence 0 otheror even aisolution of titanium salt of a. dlfferent concentration. The quantity of the hquid added is calculated so as to produce on diffusion or mixing together the desired concentration. The liquid is introduced in such a manner that the two liquids may mix together only gradually, and thus within a certain time there Will be a difference in concentrations in difi'erent parts of the solution asregards H 80 and TiO,.

- (2) Inanother or modified method the solution is concentrated by evaporating or boiling and may even'become thick like a paste. When the necessary quantityof water has been eliminated according to the object,

the solution is mixed with'a Smallergequal or larger quantity of .water than that eliminated.

One'of the liquids must be at that time at atemperatureabove 60 -C.usually the conor containing some-substances, suc nium salt or the like. The proportions of the two liquids are selected so as'to have the desired concentration, both in TiO and H SO in the final state after the com lete mixing. The mixing should be effected airly quickly in order that the titanium hydroxide does not centrated solution. 7 The water may1 be pure as tita- 1 precipitate appreciably before the homomixin geneity of the solution is achieved and heating continued.

In both cases the hydrolytic precipitation is terminated at a temperature not far from the boiling point of the solution and in a constant volume. The yield of the precipitate reaches 85-95 per cent in a few hours in the first case and in less than one hour in the second. The various properties mentioned above are greatly improved, such as the filtrability as well as the stability of the mother liquor at dilution.

These methods are equally valid when the titanium hydroxide is precipitated in presence of other substances adapted to serve as constituents of paint pigments, (such as BaSO CASO SiQ and the like) with which it is desired to mix it very intimately. The added substances may be prepared separately or in the same apparatus in which the hydrolysis takes place.

E mamtple 1.

The solution containing Gr. per litre.

TiO, 225, Fe 5O H 80 total 440 Example 2. The solution containing Gr. per litre. Tio 180 Fe 4:2 H SO, 460

is concentrated by evaporation to half its volume. It then has the consistency of a paste. It is introduced into about twice its own volume of boiling hot water so that the concentration finally will be 300-310 gr. I-I SO per litre. The mixing is effected in such a manner as to avoid the immediate coagulation (precipitation) by delaying the from 3 to 5 minutes. It is maintained at bolling temperature, evaporatiombemg prevented. In about half an hour a yield of 85-95 per cent of titanium hydroxide is obtitanium salts may contain other substances such,'for'examp1e, as the sulfuric acid or titanium salts. In certain of the claims I have used the term solution of lesser concentration broadly as covering the diluent which is used in the process.

Having now described my invention what I claim as new and desire to secure by Letters Patent is 1. The preparation of titanium oxide or hydroxide by hydrolytic precipitation which comprises diffusing titanium from one solution into another under the action of diiferential concentration and temperature and allowing the diffusion action to continue for several minutes before mixing the solutions.

2. The preparation of titanium oxide or hydroxide which comprises the hydrolytic precipitationby diffusion of titanium from one solution into another, acz 'elerated by mix-.

ing the two solutions after allowing the diffusion to continue for about 3 to 5 minutes.

'3. The preparation .of titanium oxide or hydroxide by hydrolytic precipitation which comprises diffusing titanium from one solution into another under the action of differential concentration and allowing the diffusion action to continue for several minutes before mixing the solutions.

. 4. The preparation of titanium oxide or hydroxide by hydrolytic precipitation which comprises diffusing titanlum from one solution into another under the action of differential concentration, and allowing the diffusion action to continue for several minutes before mixing the solutions, the proportions being such as to give, upon mixing, a content of total I-I SO equal to about 300 to 310 grams per litre of solution.

5. A process for the preparation of titanium dioxide or hydroxide by hydrolytic precipitation, which comprises bringing together a solution of titanium sulfate with a solution of lesser concentration and retarding the rate of admixture so that the titanium sulfate solution is gradually diluted.

6. A process for the preparation of'titanium dioxide or hydroxide by hydrolytic precipitation, which comprises bringing together a solution of titanium sulfate with a diluent and retarding the rate of admixture so that the titanium sulfate solution is gradually diluted.

7 A process for the preparation of titanium dioxide or hydroxide by combining a solution of titanium sulfate with a solution of lesser concentration at an elevated temperature, which comprises gradually mixing said solutions.

8. In a process for the preparation of titanium dioxide or hydroxide by combining a solution of titanium sulfate with a diluent at an elevated temperature, the step which comprises gradually mixing the solution with said diluent.

9. A process for the preparation of titanium dioxide or hydroxide by hydrolytic vprecipitation, which comprises bringing together a solution of titanium sulfate with a. solution of lesser concentration and delaying the admixture of the solutions.

- 10. A prooes sforthe reparation of titani- 5 um dioxide or 11 droxidb'by hydrolytic pre- -oipitation,. whic comprises bringing together a solution of titanium sulfate with a diluent and delaying the admixture of the titanium'sulfate and the diluent. v 10 1 1. A rocess for the reparation of titaniu dioxlde or hydroxi e by'combining a solution of titanium sulfatewith'a solution of lesser-concentration at an elevated temperature and permitting difl'usion to takeplace 15 between the two solutions.

12. In a process for the reparation of ti-' tanium dioxide or hydroxi e by combining a solution of titaniuinsulfate with a diluent at an elevated temperature, the'step which comprises difiusing the solution with the 0 diluent.

' JOSEPH BLUMENFELD. 

